1. Technical Field
Various embodiments of the inventive concept relate to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a phase-change random access memory (PCRAM) device having a confined structure.
2. Related Art
With trends toward miniaturization, low-power consumption, high performance, diversification, or the like of electronic apparatuses such as computers and portable apparatuses, semiconductor memory devices that may store information have been used in the electronic apparatuses, and researches on the semiconductor memory devices have actively progressed.
As one of the semiconductor memory devices, a semiconductor memory device may store data in a data storage layer with a switching characteristic between different resistance states in response to an applied voltage or current.
Examples of the semiconductor memory device with such characteristics includes resistive RAMs (RRAMs), PCRAMs, ferroelectric RAMs (FRAMs), magnetic RAMs (MRAMs), E-fuses, or the like.
The PCRAMs among the semiconductor memory devices use a phase-change material pattern as a data storage medium. The phase-change material pattern has two stable states (an amorphous state and a crystalline state) depending on applied heat, and the semiconductor memory devices having the phase-change material pattern store data using a resistance difference between the amorphous state and the crystalline state.
Generally, a widely known phase-change material GST (Ge—Sb—Te), which is a compound of germanium (Ge)-antimony (Sb)-tellurium (Te). The phase-change material pattern may be formed by supplying source gases (for example, a gas including a Ge precursor, a gas including a Sb precursor, and a gas including a Te precursor) together with a reaction gas to an inside of a process chamber in which a semiconductor substrate including a lower electrode is supported. The Ge precursor has a ligand larger than the Sb precursor or the Te precursor.
The semiconductor memory devices may have a confined structure to reduce a reset current. Referring to FIG. 1, Ge precursors are adsorbed to each other while the Ge precursors move to be formed on the semiconductor memory device having a confined structure, that is, in a hole 25 of an interlayer insulating layer 20 formed on a semiconductor substrate 10, and thus a molecular size is increased. In FIG. 1, the reference numeral 30 is a heater formed in the hole.
If the molecular size of the Ge precursors is increased as described above, a void may be formed as illustrated in FIG. 1 when the Ge precursors are placed in the hole 25, and thus Ge metal elements may not be deposited at a desired composition ratio.